Well, I was just able to get back to this project . There were 4 nut screws on the back freezer panel two of which are ridiculously placed to thwart removal but I got them off. How does one get the plastic vent housing off the back panel ? there is no screws and it doesnt seem to have depressable clips. or does that stay with the back panel? I am now battling the ice maker which needs to be removed in order to get the back panel off (see pic). I can't seem to get the electrical connection clip to release and I assume I have to remove the ice maker as the rear panel needs to be removed by tipping the top toward the front opening as the bottom of the panel can't clear the bottom draw rails. BTW it appears to me evaporator fan is working but the fan next to compressor is not -- is that why the return may be blocked with ice because that fan is not blowing the heat generated from the compressor against that back wall and heating enough so that it does not ice up?

OK!! I got the ice maker out. My last hurdle is the vent cover in the middle of that last picture. There seems to be a "tab" right in the center of "grid". I have tried depressing it every way come SUnday and it won't pop off. It seems it needs to be removed in order to get the back panel off. I know this must sound lame to you guys. Appreciate your help.

Thanks Stoveguy... got it off doing as you suggested and as you can see from pics... is this frost the problem or is the frost there because I have had this open for a couple of hours while working on it and it is the exposure to warm air? not sure how I would check if the "return flow" is blocked? that opening certainly seems clear.

Quick update ... fins are clearing of frost since the back panel came off.... and I held the door switch down for about two minutes or so and that fan in pic did NOT start. Should it have? and how rare is it that both fans would go at the same time. and I think I've asked but is there any kind of fuse or breaker onboard that blows or trips if there was a surge when electric spiked before going off in storm?